Telephone system.



W. W. DEAN.

TELEPHONE SYSTEM.

APPLICATION FILED JAN. 23, 1904.

Patented Feb. 16, 1909.

WILLIAM W. DEAN,

OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

To all whom it may concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States of America, and resident of Chicago, county of Cook, and State of Illinois, have invented a new and useful Improvement in Telephone Systems,

and, in addition, to associate with each line,

a cut-off relay which when the operators circuit is connected with the line is operated to cut ofi the line relay to render the line signal inoperative. A central source of current common to the exchange is also normally connected with the telephone lines, but when the cut-off relay is operated the normal connection of said source is opened and a temporary connection established therewith through. the medium of the cord circuit.

Inmypresent invention I associate with each line, a line signal and a line relay, the relay controlling normally open contacts in the local circuit of said signal. In addition a cut-ofi relay is provided for each of the lines which is adapted when the operator connects her cord circuit with the line to establish a path of low resistance about the line relay, which is permanently connected in the telephone line to cause the same to release its armature and thereby open the circuit of the line signal to retire the same, or in case the line signal has not yet been operated to prevent its operation during the time that the connection is established.

In connection with the cord circuit I provide a supervisory signaling system through the medium of which, supervisory signals that are associated with the respective plugs of the cord circuit are adapted to individually indicate the condition of the subscribers telephones during conversation. A suitable ringing outfit is also provided for the operator by means of which she is enabled to call any desired subscriber.

My invention is illustrated in the accompanyingdrawing in which the figure is a diagram of a telephone system embodying my improvements.

Specification of Letters Patent. Application filed January 23, 1904. Serial No. 190,310.

Patented Feb. 16, 1909.

In this figure, L and L indicate two subseribers lines extending in two limbs 2 and 3 from their respective substations to the central oflice. At the substation each subscriber is provided with an ordinary slgnaling bell 4 and a condenser 5 in a bridge of the line conductors which is normally closed at the switch-hook 6, upon which the receiver 7 is adapted to be suspended when not in use. When the receiver is lifted from the switch-hook, it is suitably connected in circuit with the transmitter 8, the retardation coil 9 and the condenser 5. Any other suitable or desired common battery outfit may obviously be employed.

At the central om'ce the line is provided with a signal S and an answering jack J, and a plurality of multiple jacks J and J in any desired number. 'l he switchboard section of the telephone line is normally disconnected from the external section, the line conductor 2 being normally grounded through a spring of the cut-ofi' relay R, the winding of which is legged to ground from the sleeve conductor of the switchboard section, but is adapted when the said relay is operated to be disconnected from ground and connected ith the tip side of the su itchboard section. 'lhe sleeve conductor 3 of the telephone line includes the winding of the line relay R which controls through its normally open contacts the local circuit of the line signal S, and is thence connected with a second spring of the cut-off relay It, whose normal contact is joined by a branch conductor 10 with the bus bar 11 leading from the live pole of the central common battery B. W hen the said cut-oil relay is actuated, said spring is disengaged trom the conductor 10 and connects with the sleeve side of the switchboard section of the telephone line. A shunt circuit, consisting of the branch conductor 12 is adapted to be connected around the line relay R by the said sleeve spring and forward contact of said cut-oil relay It, whereby when said cut-off relay is operated, said line relay is shunted and is thereby deprived of operating current so that its armature may not be attracted and the local circuit of the line signal is opened.

Each operator is provided with a plurality of cord circuits each of which circuits is provided with an answerin plug P and a calling plug P having tip and s eeve contacts adapted to register with the corresponding contacts of the spring jacks when inserted therein. 'lhe tip contacts of said plugs are electrically united through the flexible strands t and t and the interposed condenser c, and their sleeve contacts are similarly joined by the strands s and s and the interposed condenser 0 A pair of supervisory relays r and r are together with the battery B bridged across the answering end of the cord circuit, the former relay serving when operated to open the local circuit of the supervisory signal S associated with the plug P and the latter relay serving when excited to close the circuit of said signal. A similar pair of supervisory relays r and r are together with a second common battery bridged across the calling end of the cord circuit and control in a similar manner the supervisory signal S which is associated with the calling plug 1. lhe operators set comprising a head receiver 13, the secondary of an induction coil 14, and a suitable condenser are adapted to be bridged across the calling end of the cord circuit through the medium of any suitable listening key, while her transmitter 15 and the primary u inding of her induction coil are ada )tdCl to be included in a local circuit with any suitable source or current, which may be either the battery B or B A ringing generator 16 is adapted to be connected between ground and the tip contact of the calling plug through the employment of a suitable ringing key 17, the sleeve spring of which key at the same time serves to connect the sleeve contact of the plug with the auxiliary conductor 18, containing a suitable resistance and which is connected w ith the second common battery lead or omnibus bar 11 that leads from the live pole of the battery B In the operation of the system, the sub scriber upon line L for example, takes up his receiver, and thereby completes a path for current over his metallic line from the live pole of the battery B over conductors 11, 10 and 3, including the winding of the line relay R thence through the substation devices and back over the line conductor 2 to the central oflice and ground. The line relay R is thus operated and serves to close the local circuit of the line signal S which is lighted to attract the attention of the operator. Upon observing this signal the operator inserts the answering plug P of her cord circuit in the answering jack of the telephone line and depresses her listening key to connect her set with the cord circuit. The insertion of the said plug includes the battery B together with supervisory relay r and the cut-off relay it in a local circuit, thus operating the cut-oil relay and thereby severing the normal connections of the line conductors 2 and 3 and joining them With the switchboard section of the telephone line. Simultaneously the shunt '12 is closed about the line relay R which being thus deprived of operating current releases its armature and opens the local circuit of the line signal S to retire the same. The supervisory relay r is actuated at the same time but owing to the presence of the current flowing over the metallic line and through the tip supervisory relay 1, the signal S is prevented from operating and accordingly remains inert. Upon learning the order of the calling subscriber the Wanted line is tested in the usual manner by touching the tip of the calling plug to the test ring of the multiple jack at the section of the switchboard. at which the connection has been initiatet, a click being received by the operator when the line is busy and no click when the line is idle. Finding the line idle the calling plug is inserted and the ringing hey depressed. Any ordinary type of ringing key may be employed, but preferably one in which both springs are simultaneously operated. Thus the ringing generator is connected with the tip side of the line and sends current out over the telephone line with return through the sleeve conductor of the switchboard section, the forward portion of the sleeve strand of the cord circuit, conductors l8 and 11 and through the battery B to ground. At the same time the cut-oil relay of the called line is maintained actuated by current from the Jattery B over conductors 11 and 18 and through the cuto i relay to ground. The ringing current is thus shunted around the supervisory relay r to prevent the same from chattering. After the subscriber has been called but before his response, current flows through the supervisory relay 7* and the cut-oil relay of he telephone line in a local circuit, said supervisory relay serving to close the circuit of the supervisory signal S which is lighted to indicate to the operator that the subscriber has not yet responded. As soon as he does respond current is permitted to flow over his metallic ine and the supervisory relay r is actuated to open the local circuit of and retire the said signal S During conversation the batteries B and B are sending current out over the two telephone lines to provide the substation instruments with operating current and to actuate the several relays at the central oiiice. The voice currents are readily propagated from one circuit to the other through the medium of the condensers c and c in the cord circuit. At the termination of the conversation, the subscribers return their receivers to the switch-hooks with the result that the metallic circuits are open to steady currents and the supervisory relays r and r in the cord circuits are denergized thus permitting the lighting" of the supervisory signals S and S since the said supervisory relays r and r remain actuated. Upon observing these signals the operator withdraws the plugs P and P thus again opening at the relays 1 and r the local circuits of the supervisory signals and retiring the same. The cut-oil relays are simultaneously deenergized and all parts are restored to normal condition.

Having thus described my invention what I claim and desire to secure by Letters Patent is 1. In a telephone system, the combination with a telephone line, of a central source of current therefor, a cut-off relay having contacts normally connecting the poles of said source with the limbs of said telephone line, and a line relay normally in series with the line and adapted to be shunted by the actuation of said. cut-oil' rclay, substantially as described.

2. In a telephone system, the combination with a telephone line, of a source of current at the central office, a cut-off relay having contacts normally connecting said source with the limbs of the telephone line, a line relay normally in series in the line, a cord circuit adapted when connected with the line to complete the energizing circuit for said cut-oil relay, the actuation of said outoff relay being adapted to complete a shunt about the line relay, whereby said relay becomes inoperative, substantially as described.

3. In a telephone system, the combination with a telephone line, of a source of current at the central oflice, a cut-oil relay having contacts vnormally connecting the limbs of said line with the poles of said source, a line relay adapted to receive current from said source when the cut-oil relay is in its normal position and the line is closed at the substation, the actuation of said cut-off relay being adapted to sever the normal connection of said line with said source and to complete a shunt about said line relay whereby it becomes inoperative, substantially as described.

4. In a telephone system, the combination with a telephone line, of a cord circuit adapted to be connected therewith, a source of current at the central office, a cut-off relay for the line having contacts normally connecting a limb of said line with a pole of said source, a line relay in said limb of the line adapted to be actuated when the line is closed at the substation, said cut-off relay being adapted to be actuated to complete a shunt about the line relay and to sever the normal connection between said limb of the line and said pole of the source when the cord is connected with the line, substantially as described.

5. In a telephone system, the combination with a telephone line, of a line relay with its coil normally in series with said line, a central source of current normally connected with said line through the coil of said line relay, a cut-off relay adapted by its actuation to remove said source from its connection with said line relay and to place a shunt about the coil thereof, whereby said line relay becomes deenergized, substantially as described.

6. In a telephone system, the combination with a telephone line, a central source of current, a line relay normally connecting said line with said central source, a single coil cut-oil relay also associated with the line adapted by its actuation to shunt the coil of .said line relay, whereby the latter may not be energized, substantially as described.

7. In a telephone system, the combination with a telephone line, of a line relay nor mally in series with the line, a cut-off relay having its coil connected between one of the limbs of the telephone line and a third conductor during conversation, said cut-olf relay having contacts normally in series with the line relay and also having contacts adapted to complete a shunt about said line relay during conversation, whereby the line relay is deprived of actuating current, substantially as described.

8. In a telephone system, the combination with a telephone line, of a cut-off relay for the line, a source of current at the central office connected between the limbs of said telephone lineby contacts of said cut-oil relay, a line relay having its coil normally in series with the telephone line, a conductor permanently connected with the line at a point beyond the coil of said line relay and connecting with a normally open contact of said cutoff relay, said conductor being adapted to form a shunt circuit about the coil of said line relay when the cut-off relay is actuated, whereby the line relay will become denergized, substantially as described.

9. In a telephone system, the combination with a telephone line, of a source of current at the central ofiice normally connected with a limb of the line through contacts of the cut-oil relay, a line relay in a limb of the line adapted to be shunted by the actuation of the cut-oil relay, the actuation of said cutoil relay being also adapted to interrupt a normal connection between said source and said line, substantially as described.

Signed by me at Chicago, county of Cook, State of Illinois, this 31st day of December WILLIAM W. DEAN. Witnesses:

E. A. GARLOCK, ROBERT LEWIS Anne. 

